Fix a NoFall crash when disconnecting from the server (#6253)

Author: aazz180

src/main/java/meteordevelopment/meteorclient/systems/modules/movement/NoFall.java

@@ -114,6 +114,7 @@ public void onDeactivate() {
 
     @EventHandler
     private void onSendPacket(PacketEvent.Send event) {
+        if (mc.player == null) return;
         if (pauseOnMace.get() && mc.player.getMainHandStack().getItem() instanceof MaceItem) return;
         if (mc.player.getAbilities().creativeMode
             || !(event.packet instanceof PlayerMoveC2SPacket)